Disposable absorbent articles (e.g., diapers, training pants, pant-like articles, feminine hygiene products, and adult incontinence articles) are commonly used to absorb and contain body exudates. Such articles are typically used to prevent body exudates from soiling, wetting, or otherwise contaminating clothing or other articles such as bedding that may come into contact with the absorbent article. However, it is known that, in at least some instances, bodily exudates may escape the boundaries of an absorbent article due to, for example, leakage from gaps between the article and a wearer's skin and/or from seepage through the material that makes up the absorbent article. Seepage may be caused by the inability of one or more of the materials used in the construction of the absorbent article or absorbent article component to provide an effective barrier to such bodily fluids. For example, with sufficient pressure or loading, urine may penetrate through absorbent article components or component portions, which are intended to prevent the passage of urine (e.g., the leg cuff or outer cover of a diaper). Additionally, loose fecal matter that is not easily absorbed by the absorbent article may remain on top of the article's liquid receiving member (e.g., topsheet). During the course of wearing the article, fecal matter may spread over the liquid receiving member and may even leak from the article.
Traditional absorbent articles such as diapers typically include one or more barrier members (e.g., barrier leg cuffs, gasketing cuffs, secondary topsheets, core covers, outer covers, and portions of these). Other features such as pockets, spacers, transverse barriers, apertured topsheets and the like may be included to isolate, immobilize, and/or confine body exudates such as fecal matter. Attempts have been made at improving the barrier characteristics of absorbent article components and/or component portions by selecting barrier member material(s) and/or combinations of material that provide a particular benefit. For example, an absorbent article component may be made substantially liquid impervious through the use of polymeric films, but such films may also be vapor and air impervious. Thus, even though the article may have suitable barrier properties, it may occlude the skin of the wearer, resulting in diaper rash and/or other undesirable effects. The use of nonwoven materials is common in absorbent articles since they typically provide vapor and air perviousness (i.e., they are “breathable”), but nonwovens may not provide suitable imperviousness to liquids in at least some instances.
One way to improve the liquid imperviousness of a nonwoven is to treat the nonwoven with a composition that renders the nonwoven, or portions thereof, more hydrophobic, for example, by coating the nonwoven with a composition containing one or more silicone polymers. Examples of surface coatings for improving the barrier properties of a nonwoven are disclosed in U.S. Publication Nos. 2005/0177123 and 2006/0189956. Known silicone containing coatings are typically applied to the nonwoven as a hydrophilic solution (e.g., an emulsion of a polar liquid component such as water, a non-polar liquid component such as silicone oil, and other optional ingredient(s) such as surfactant(s) and stabilizer(s)). The active hydrophobic component in such solutions (e.g., a silicone composition) is typically present as a relatively small weight percentage of the solution (e.g., less than 50%, 40%, or even 20%), based on the total weight of the solution. Thus, in order to provide the desired amount of the active hydrophobic component per unit area of nonwoven substrate, it may be necessary to apply a relatively large amount of an aqueous solution to the nonwoven, and since the aqueous component of such solutions is typically removed from the substrate (e.g., by drying), the cost, amount of waste, and/or process complexity associated with removing the aqueous component may be undesirably increased. Further, in at least some instances, nonwovens are formed from hydrophobic materials (e.g., polyolefin fibers), and applying an aqueous solution to the hydrophobic nonwoven may cause the solution to undesirably spread across the substrate resulting in a non-uniform or even random distribution of the active hydrophobic component in the solution. The relatively non-uniform distribution of the active hydrophobic component may result in one or more portions of the material being substantially untreated and therefore subject to an increased potential for liquid to undesirably pass through the substrate or a portion thereof. Still further, aqueous solutions typically include additional ingredients such as surfactants and other additives to stabilize the solution. Surfactants are known to reduce the interfacial tension between different liquids in a composition and facilitate spreading of the composition. When exposed to bodily fluids such as urine, surfactants and/or other ingredients in aqueous solutions may be transported away from their intended location (e.g., they may migrate to the absorbent core and/or some other absorbent article component). The migration of the surfactants and/or other ingredients from their intended location may undesirably impact the barrier properties of the portion of the absorbent article that the surfactant and/or other ingredients are migrating from, as well as the portion of the absorbent article that the surfactant and/or other ingredients are migrating to.
Accordingly, it would be desirable to provide a method for improving the barrier properties of a nonwoven material. It would also be desirable to provide a method for providing a more uniform hydrophobic surface coating on a surface. It would further be desirable to provide a method for applying a hydrophobic surface coating composition to a material surface without the migration of actives.